A liquid crystal display (LCD) device, such as a liquid crystal (LC) television, includes an LCD panel and a backlight module. The backlight module using a light emitting diode (LED) as a backlight source needs to use an LED backlight driving circuit. A typical LED backlight driving circuit includes a constant current driver chip. As shown in FIG. 1, the constant current driver chip includes two output pins. A first output pin outputs a gate signal adjusting a driving voltage of the LED backlight driving circuit, and a second output pin outputs a pulse-width modulation (PWM) dimming signal adjusting brightness of an LED lightbar. The typical LED backlight driving circuit needs two pins of the constant current driver chip, which increases area and cost of the constant current driver chip.